The invention relates to a blade-type focal-plane shutter having a plurality of opening blades telescopically movable in front of the film.
In photographic cameras with photoelectrically regulated exposure times it is known to illuminate the photoelectric transducer by the light reflected by the leading and partially mirror-coated shutter curtain. This surface mirror-coating known in curtain-type shutters is not usable for telescopically mutually movable opening blades, because the friction of the blades on one another attacks the surface mirror-coating. To compensate for the difference between the reflection capacity of an opening curtain which is not especially pre-treated and the reflection capacity of the film, it is further known to switch off composite capacitors by switch actuation during the opening movement of the shutter. The moment of this switch actuation is not precisely determinable, on account of the high running speed of the opening blades.
The invention has the purpose of effecting the illumination of the photoelectric transducer by light reflection in the region of the film plane even before and during the opening movement of the shutter, and has the problem of providing a measure suitable for blade-type focal-plane shutters.